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Food Chains/Transcript
Transcript An animation shows a forest. Plants, animals, and birds abound. Text reads: The Mysteries of Life with Tim and Moby. The view switches to show a man, Tim, standing next to a robot, Moby. Moby is holding a shovel and has three blue lights on his chest. Tim is wearing a white T-shirt with a drawing of a whale swallowing a fish in the center. Tim is also wearing a hat. There are mountains and a lake in the background. Tim reads from a typed letter. TIM: Dear Tim & Moby, Are plants always at the bottom of the food chain? From, Dwog. The letter indicates that it arrived via the Internet. TIM: In any given ecosystem, all living things are linked together by what they eat. Organisms depend on each other for nourishment to survive, and this joins them together in something called a food chain. A diagram in the shape of a pyramid is shown. In the top row of the pyramid is a drawing of a brown bear. In the row below that are two medium-sized fish. Below that is a row of five small fish. In the bottom row of the pyramid are some aquatic plants, plankton, and a shrimp. TIM: In this one lake, there are many different food chains at work. Plant plankton are eaten by small animals, say … shrimp. A close-up of the lake fills the screen. An animation shows a shrimp swimming towards and then eating some plant plankton. TIM: Shrimp are eaten by fish, which are eaten by even bigger fish until the bears that hang around the lake decide to go fishing. The shrimp gets eaten by a fish which gets eaten by an even bigger fish. Then the head of a large brown bear enters the water and eats the large fish. MOBY: Beep? The view switches back to Tim. TIM: What would happen if we caught every last shrimp in the lake and had a big barbeque? Well, the fish that depend on the shrimp for food would go hungry, and the population would dwindle. And if there weren’t any fish, then the bears would go hungry too. An animation of a bear rubbing its tummy is shown. TIM: Disruptions in the food chain can work the other way, too. The pyramid showing the food chain reappears on the screen. Only the top three levels are shown. TIM: If all the bears ran off to join the circus, the population of large fish that the bears normally eat would grow out of control. The top level of the pyramid, containing the bear, disappears. The next level that had two fish in it expands to show four fish. TIM: They'd get themselves into trouble by quickly eating all their food. The bottom layer of the pyramid shows eight small fish. One by one they disappear until none are left. TIM: Food chains aren't the whole story. They often combine to form complex food webs, containing many interconnected and overlapping chains. A diagram showing many animals, plants, fish, and birds is shown. Red arrows point from each figure to one or more entities that can eat that figure. For example, an arrow shows that a fox can eat a rodent which can eat a plant. A duck can also eat that same plant. TIM: A food web has three major elements: producers, consumers, and decomposers. The screen splits into three frames. The left frame shows some producers: two different plants. The middle frame shows some consumers: a bird, a human, and a fox. The right frame shows some decomposers: a bacterium, a fungus, and a moldy substance. TIM: Plants make up the bulk of the world’s producers. A close-up of a leaf is shown. TIM: They're able to make their own food using photosynthesis, a process that harnesses the energy of the sun. Yellow rays of sunlight are shown beating down on the leaf. Text reads: photosynthesis. TIM: Producers are the largest part of any food web, and you can find them at the bottom of all food chains. Various plants are shown. Superimposed on the picture is the drawing of the four-tiered food chain pyramid, with an arrow pointing from the top to the bottom. The bottom row now contains plants, algae, and a flower. The view switches back to show Tim and Moby. TIM: Organisms that eat other living organisms are called consumers. They can't make their own nourishment from sunlight, so they get it by eating the producers. Humans are consumers, as well as birds and cows and millions of other species. Four drawings appear on the screen in each quadrant of the screen. They are of a man and a woman, a bird, a cow, and a fish. TIM: Primary consumers eat the producers. The view zooms in on the cow. TIM: Animals that eat plants are examples of primary consumers, and they’re also called herbivores. An animation shows a cow eating grass. TIM: Secondary consumers are the organisms that eat the primary consumers; these are carnivores, or meat-eaters. An animation shows a lion sneaking up on a deer. The view switches back to Tim and Moby. TIM: Some animals, like humans, are called omnivores because they eat both meat and plants. There are other kinds of consumers, too. Parasites are small organisms that live on the bodies of other organisms, using up the victims’ energy. An animation shows a tick feeding between the hairs growing on the back of an animal. TIM: Scavengers eat the carcasses of other dead animals. An animation shows two vultures picking at the skeleton of an animal. Another vulture can be seen circling in the sky. TIM: Decomposers are mostly bacteria and fungi. An animation shows a number of grey ovals, representing bacterium, wiggling. TIM: Decomposers cause the mold that grows on your bread but they also do all sorts of good stuff like breaking down dead animals and plants into reusable elements, and recycling nutrients back into the food web. An animation shows mushrooms growing in a forest next to a dead animal and a decaying log. The view shifts back to Moby who is holding a fishing pole. TIM: Humans have to be more careful to protect every species in the world. Just about every species on the planet, no matter how insignificant it seems, is vital to the food web. The diagram of the food web is shown. There are images of many plants, animals, birds, and fish shown with arrows between some of them. TIM: If even the smallest plant or animal becomes extinct, the consequences will ripple throughout the food web, causing environmental chaos for every species concerned, including us! The plants, animals, birds, and fish within the food web diagram begin to disappear along with their arrows, one by one, until none are left. The view then switches back to Tim. Moby can be seen in the background, standing in the lake and fishing. TIM: It's hard to predict exactly what will happen, but one thing's for sure: I don't want to be around if that bear doesn't get his dinner! The view switches to a close-up of Moby fishing. A bear approaches him. Moby hands the bear his fishing rod, and then quickly disappears off screen. Category:BrainPOP Transcripts Category:BrainPOP Science Transcripts